1. Field of the Invention
The present invention relates to a polling control method which is suitably applied to a case where a transmission of various data items is made by means of, for example, a radio signal to thereby construct a local area network (LAN) among a plurality of appliances, and a transmission control apparatus and a transmission apparatus to each of which this polling control method is applied.
2. Description of the Related Art
Conventionally, in a case where constructing a local area network within a relatively narrow range such as a home, an office or the like so as to enable a transmission to be made, among a plurality of appliances such as various video appliances, personal computer apparatuses and their peripheral apparatuses or the like, of data that are handled by such appliances, instead of causing direct connections to be made among the appliances by the use of some signal line or other it is sometimes arranged to enable data transmission to be made through radio transmission by connecting radio signal transmission and reception apparatuses (radio transmission apparatuses) to the respective appliances.
Since a local area network is constructed through the operation of radio transmission, it is unnecessary to make direct connections among the respective appliances by means of signal lines or the like and it is possible to simplify the construction of the system.
Meanwhile, in a case where a plurality of radio transmission apparatuses are prepared and a local area network has been made up of these apparatuses, when signals are simultaneously transmitted from a plurality of transmission apparatuses, there is a possibility that a transmission error will occur. For this reason, it is necessary to perform access control by some method or other of the communication made among the respective transmission apparatuses within the network.
As the access control method that is conventionally known, there is a method of unitarity managing, in, for example, a small-scale radio network, the communication among the respective transmission apparatuses (nodes) within the network by the use of a transmission apparatus (root node) located at a central part of the star-connected version. As a general interference avoiding method in this case, there was used a band reserving method in which a band for each transmission path is reserved regardless of the presence or absence of transmission data, whereby transmission is performed through the use of this reserved band. However, this method had the problem that in even a case where no data exists that is to be transmitted, there is the need to ensure the band for use on a corresponding transmission path, with the result that the network resources are used for nothing and therefore the efficiency with which such resources are used is very low.
As the access method that has solved the above-described problem, there is a method of performing communications within the network through the performance of a polling control. In this method, it is arranged to use one arbitrary transmission apparatus within the network as a control station (root node) and for the root node to transmit a control signal for performing polling sequentially to other nodes within the network to thereby cause the transmissions from the respective nodes to be performed sequentially through the performance of the polling. By performing the transmission processing through the performance of the polling, it is possible to improve the transmission efficiency.
On the other hand, in even a case where a construction is made wherein the access control is performed by polling, there is the problem that when the number of the transmission apparatuses (nodes) within the network becomes large, the transmission efficiency becomes inferior. Namely, if the number of the nodes within the network is small, even when the polling is performed sequentially with respect to every node within the network, this does not raise a problem which is so serious. However, assuming a case wherein there are, for example, a number of nodes within the network and only a small number of nodes alone among them each have data therein that is to be transmitted therefrom, the amount of polling performed with respect to the nodes having no transmission data comes to increase and this is followed by transmission in large number of only the control signals for use on the polling control alone. This inconveniently decreases the transmission efficiency of the network and necessitates the transmission by the root node of the control signals for polling in large number and this imposes a heavier load onto the root node.
Also, in a case where each node within the network is constructed as being, for example, portable, it is necessary to perform movement management for the node through the operation of the root node and therefore it is necessary for each node to make a return transmission of a response signal with respect to polling performed from the root node. In this way, in the case of the construction wherein it is at all times necessary to make a return transmission of a response signal with respect to polling, even a node having no transmission data therein is always needed to perform communication processing for responding to polling. For this reason, the power consumption of each node inconveniently increases.
Accordingly, an object of the present invention is, in a case where access management for communication is performed by polling, to enhance the transmission efficiency within the network and so on.
A polling control method of the present invention is arranged to define a managing data transmission area and a data transfer area within a frame period, perform within the managing data transmission area the transmission of data for determining a state of polling control, and perform within the data transfer area the communication among a plurality of the communicating stations through the polling control of a control station based on the data transmitted within the managing data transmission area.
According to the polling control method of the present invention, it is possible for the control station to obtain through the communication made using the managing data transmission area information that is necessary when performing the polling control within the data transfer area.
Also, a transmission control apparatus of the present invention is arranged to receive data for determining a state of polling control at a timing determined as the managing data transmission area within the frame period and transmit a polling control signal for causing a transmission to be made from a terminal apparatus at a timing determined as the data transfer area based on the data that has been received within the managing data transmission area.
According to the transmission control apparatus of the present invention, a state of polling control is determined based on the data that has been received in the managing data transmission area within the frame period and, in the state wherein this determination has been made, the polling control of the terminal apparatus is performed with the use of the data transfer area.
Also, the transmission apparatus of the present invention, a frame period is set based on a prescribed synchronizing signal and a managing data transmission area and a data transfer area are set within the set frame period, and there is transmitted within the managing data transmission area a signal for ensuring a transmission path and there is performed data transmission within the data transfer area based on a polling control signal from the control apparatus.
According to the transmission apparatus of the present invention, in a case where there is the need to ensure a transmission path, a corresponding signal is transmitted within the managing data transmission area within the frame period and, within the data transfer area, there is performed a wait processing of waiting until a polling control signal is transmitted.